Orbit passes from product

Microwave Toolbox
#1

How to get type of orbit passes from GRD product? I mean ascending/descending.

#2

Right click on a product and see properties or open the Abstracted Metadata and find the ‘pass’ field.

1 Like
#3

Yep, thx I found it in manifest.safe file (tag s1:pass, line 154).

#4

Hi,
how to open manifest.safe file?

#5

simply click File > Open and select it.

#6

Hi ABraun,
thanks i could not open manifest file but i have opened the calibration vector list in file viewer and exported to excel.

I am confused about this data arrangement. there are 27 vector lists… starts from “line 0” each contains 642 pixel value sets like 0 40 80…upto 25600 25612… next vector list’ line no is 671 and another 642 values of pixel ,sigma0,gamma0… How it is organised ?
I have read the "Sentinel-1_Product_Specification "document but i don find much info on pixel organisation pls help me in understanding this pixel organisation of calibration vector list ( GRDH )
Thanks in advance

#7

to be honest, I have no idea what you are trying to do. :slight_smile: Maybe you can tell us a bit about your intention first.

#8

I am trying to extract the sigma0 value ( around the target) from the calibration vector list… so that i can compare with the results what i have got through Matlab… …
In the calibration vector list i could locate the line of my target which is approx. matching… But how to locate the pixel value and corresponding sigma0 ?
My doubt is completely about how the pixels are organised in the calibration vector list?

Thanks in advance

#9

You need to generate and save the calibrated Sigma0 values in SNAP, please consult the tutorials for this.

#10

Hi, the ESA document ‘Radiometric Calibration of S-1 Level-1 Products Generated by the S-1 IPF’ might be useful - see https://sentinel.esa.int/documents/247904/685163/S1-Radiometric-Calibration-V1.0.pdf.

#11

Hi Peter
Thank you. I have already read the document n I followed the steps according to dat but I was stopped to get the corresponding sigmanot for particular region pixels. Because pixel values are only up to 25612(grouped as 40) of line 0 in the first vector list…and in the next vector list line no is 671 and again another 25612 pixels…
So the pixels corresponding to line 1to 670 where is it present or how the pixels are grouped…
Pls any one let me know…
If I need to go through the tutorials ping me the link because so far I found the tutorials on usage of snap basics

#12

Hi, The calibration vectors are organised by (i) azimuth pixel coordinate and then (ii) by range pixel coordinate in the form of a grid. The easiest approaches you can take to calculate the sigmaNought value for your pixel coordinate, that is not at one of the grid points, is to just find the nearest value to your pixel coordinate. So, for example, if your coordinate is at line 50 and range pixel value 10 (i.e. at 50,10) , you use the values for line 0 and range pixel value 0. However, if your are at (650,10) you use the values for line 670 and pixel value 0. This is the nearest neighbour method.

The spacing of the grid is designed so that there is very little difference between grid points and so the nearest method will not lead to significant errors. A more robust method would be to use bi-linear interpolation using the 4 grid points surrounding you pixel. However, I would suggest you use the nearest neighbour method.